The Experts below are selected from a list of 95517 Experts worldwide ranked by ideXlab platform
Amr S. Helmy - One of the best experts on this subject based on the ideXlab platform.
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single sided Bragg reflection waveguides with multilayer core for monolithic semiconductor parametric devices
Journal of The Optical Society of America B-optical Physics, 2012Co-Authors: Payam Abolghasem, Amr S. HelmyAbstract:We propose and examine single-stack matching-layer enhanced Bragg reflection waveguides (BRWs) as a platform for integrated parametric devices. The proposed designed is asymmetric in geometry, where a multilayer core is surrounded by a single-layer upper cladding and a lower quarter-wave Bragg mirror. The propagation of the Bragg mode in the new design relies on total internal reflection from the upper cladding and Bragg reflection from the lower periodic cladding. Analytical expressions for modal analysis of TE- and TM-polarized Bragg modes are derived. An AlxGa1−xAs second-harmonic generation device is theoretically examined to highlight nonlinear performance of the new design, and it is compared to symmetric phase-matched BRWs reported to date. The application of the same structure for generation of anticorrelated photon pairs is discussed.
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far field of Bragg reflection waveguides characteristics and closed form approximation
Journal of Lightwave Technology, 2011Co-Authors: Nima Zareian, Payam Abolghasem, Amr S. HelmyAbstract:A comprehensive study of the far-field diffraction pattern of Bragg reflection waveguides is presented. Using a Gaussian approximation of the near-field profile, an analytical formula for the far-field pattern of the fundamental Bragg mode is obtained. The proposed closed-form representation offers a powerful technique for examining the far-field characteristics, which provides insight into the design optimization of Bragg reflection waveguides.
Stephen F Collins - One of the best experts on this subject based on the ideXlab platform.
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numerical investigation on the effects of fabrication conditions on fiber Bragg grating spectra using the phase mask technique
Applied Optics, 2013Co-Authors: Betty Kouskousis, Stephen F Collins, Daniel J Kitcher, Gregory W BaxterAbstract:A numerical investigation on how fiber Bragg grating fabrication conditions using the phase mask technique affect the harmonic components of the Bragg wavelength is presented. Both the properties of the phase mask and saturation effects are investigated to determine the underlying cause of the rise of various harmonic reflections other than the Bragg wavelength. Results are compared with published data by various authors.
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Fabrication of a π-phase-shifted fiber Bragg grating at twice the Bragg wavelength with the standard phase mask technique
Optics Letters, 2009Co-Authors: Zourab Brodzeli, Betty Kouskousis, Scott A. Wade, Gregory W Baxter, Claire Rollinson, Stephen F CollinsAbstract:A pair of reflection peaks/transmission dips, at twice the Bragg wavelength, were observed in spectra of a Type I fiber Bragg grating written with the standard phase mask technique. The occurrence of two peaks/dips, rather than one, is attributed to the interleaved refractive index modulations along the fiber core, with the periodicity of the phase mask that has been observed previously in images of gratings that cause destructive interference in a reflected wave at the Bragg condition owing to the π phase difference between the grating phases. Thus the standard phase mask technique produced an alternative type of π-phase-shifted grating at twice the design Bragg wavelength.
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Occurrence of features of fiber Bragg grating spectra having a wavelength corresponding to the phase mask periodicity
2008 1st Asia-Pacific Optical Fiber Sensors Conference, 2008Co-Authors: Sui P. Yam, Zourab Brodzeli, Scott A. Wade, Gregory W Baxter, Stephen F CollinsAbstract:Use of a phase mask with 536 nm uniform pitch allowed the fabrication of a fiber Bragg grating for use at a Bragg wavelength of 785 nm. Reflection and transmission features at 1552 nm, i.e. twice the Bragg wavelength, associated with the phase mask periodicity were observed. However, when phase mask orders other than plusmn1 were absent during fabrication the features at 1552 nm were not evident.
Zhipeng Leng - One of the best experts on this subject based on the ideXlab platform.
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optical fiber Bragg grating pressure sensor
2011Co-Authors: Hongwei Li, Zhipeng LengAbstract:The utility model discloses an optical fiber Bragg grating pressure sensor. The sensor comprises a shell, an elastic diaphragm, a first optical fiber Bragg grating and a second optical fiber Bragg grating, wherein two hard braces for connecting the first optical fiber Bragg grating are arranged on the bottom of a cavity of the shell, the elastic diaphragm is connected with the top end of the shell, and two bosses for connecting the second optical fiber Bragg grating are arranged on the lower surface of the elastic diaphragm. The utility model has the advantages that the second optical fiber Bragg grating is connected between the two bosses, so that the Bragg grating of the second optical fiber Bragg grating strains uniformly when pressure is uniformly applied on the elastic diaphragm, and measurement accuracy and measurement flexibility can be effectively improved; the Bragg grating of the first optical fiber Bragg grating only used for measuring temperature and the Bragg grating of the second optical fiber Bragg grating used for measuring temperature and pressure are designed to be in the same vertical position, and the problem of temperature cross sensitivity can be successfully solved.
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fiber Bragg grating pressure sensor and corresponding measuring method thereof
2011Co-Authors: Hongwei Li, Zhipeng LengAbstract:The invention discloses a fiber Bragg grating pressure sensor and a corresponding measuring method thereof. The sensor comprises a shell, an elastic membrane, a first fiber Bragg grating and a second fiber Bragg grating, two hard upright columns for connecting the first fiber Bragg grating are arranged at the bottom of a cavity inside the shell, the elastic membrane is connected with the top end of the shell, and two bosses for connecting the second fiber Bragg grating are arranged on the lower surface of the elastic membrane. The fiber Bragg grating pressure sensor has the advantages that the second fiber Bragg grating is connected between two bosses, when the elastic membrane is pressed uniformly, the Bragg grating of the second fiber Bragg grating can be stressed uniformly, so as to effectively improve the measuring precision and the measuring sensitivity; and the Bragg grating of the first fiber Bragg grating only for measuring temperature and the Bragg grating of the second fiber Bragg grating only for measuring temperature and pressure are positioned on the same vertical position, so as to successfully solve the temperature intercross sensitivity problem.
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constant strength beam based fiber Bragg grating pressure sensor
2011Co-Authors: Hongwei Li, Zhipeng LengAbstract:The utility model discloses a constant strength beam-based fiber Bragg grating pressure sensor which comprises a shell, an elastic diaphragm, an L-shaped constant strength beam and a fiber Bragg grating, wherein the top end of the shell is provided with an opening, the opening and the inner space of the shell form into a cavity, the elastic diaphragm covers the opening, the constant strength beam is arranged in the cavity, the free end of a beam arm of the constant strength beam is provided with a press block, the lower surface of the elastic diaphragm is provided with a rigid boss which is closely connected with the press block, the fiber Bragg grating is mainly formed by the series connection of two Bragg gratings with the completely same temperature gradient by an optical fiber, and the two Bragg gratings are respectively connected with the upper surface and the lower surface of the beam arm. The constant strength beam-based fiber Bragg grating pressure sensor has the advantages that the elastic diaphragm is rigidly connected with the beam arm during designing, thereby being capable of not only improving the measuring precision, but also reducing the technological difficulty. The fiber Bragg grating mainly comprises the two Bragg gratings with the same temperature gradient, so that the constant strength beam-based fiber Bragg grating pressure sensor can solve the problem of the crossover sensibility of the temperature during measuring.
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optical fiber Bragg grating pressure sensor and corresponding measurement method thereof
2010Co-Authors: Hongwei Li, Zhipeng LengAbstract:The invention discloses an optical fiber Bragg grating pressure sensor and a corresponding measurement method thereof, and the sensor comprises a housing, an elastic diaphragm, an L-shaped uniform strength beam and an optical fiber Bragg grating, wherein an opening is arranged at the top end of the housing, the opening and internal space of the housing constitute a cavity body, the elastic diaphragm covers the opening, the uniform strength beam is arranged in the cavity body, a pressure block is arranged at the free end of a beam arm of the uniform strength beam, a hard boss which is tightly connected with the pressure block is arranged on the lower surface of the elastic diaphragm, the optical fiber Bragg grating is mainly constituted by connecting two Bragg gratings with the identical temperature gradient in series through an optical fiber, and the two Bragg gratings are respectively connected on the upper surface and the lower surface of the beam arm. The sensor has the advantages that the elastic diaphragm is in rigid connection with the beam arm during the design, thereby not only improving the measurement precision, but also reducing the process difficulty; as the optical fiber Bragg grating is mainly constituted by the two Bragg gratings with the identical temperature gradient, the sensor can solve the temperature cross sensitivity problem during the measurement.
Waclaw Urbanczyk - One of the best experts on this subject based on the ideXlab platform.
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fabrication of multiple Bragg gratings in microstructured polymer fibers using a phase mask with several diffraction orders
Optics Express, 2013Co-Authors: Gabriela Statkiewiczbarabach, Karol Tarnowski, Dominik Kowal, Pawel Mergo, Waclaw UrbanczykAbstract:We demonstrate for the first time a possibility of fabrication of Bragg gratings in polymer microstructured fibers with multiple reflection peaks by using He-Cd laser (λ = 325 nm) and a phase mask with higher diffraction orders. We experimentally studied the growth dynamics of the grating with the primary Bragg peak at λB = 1555 nm, for which we also observed good quality peaks located at λB/2 = 782 nm and 2λB/3 = 1040 nm. Temperature response of all the Bragg peaks was also investigated. Detailed numerical simulations of the interference pattern produced by the phase mask suggests that the higher order Bragg peaks originate from interference of UV beams diffracted in ± 1st, ± 2nd orders. We also demonstrated the grating with the reflection peak at λB/2 = 659 nm, which is the shortest Bragg wavelength ever reported for polymer microstructured fibers. This peak was observed for the grating with primary Bragg wavelength at λB = 1309 nm.
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Transversal load sensing with fiber Bragg gratings in microstructured optical fibers
2009Co-Authors: Tomasz Nasilowski, John Wojcik, Francis Berghmans, Karima Chah, Herman Terryn, Waclaw Urbanczyk, Martin Becker, Wim De Waele, Hartmut Bartelt, Hugo ThienpontAbstract:We present fiber Bragg grating based transversal load sensing with a highly birefringent microstructured optical fiber. For the bare fiber, the change of the Bragg peak separation under a transverse line load was simulated with a finite-element model and experimentally verified. We also show that microstructured optical fibers with fiber Bragg gratings can be successfully embedded in a carbon fiber reinforced composite material. The linear dependence of the Bragg peak separation to a transversal stress in the composite sample was measured to be 15.3 pm/MPa.
Gregory W Baxter - One of the best experts on this subject based on the ideXlab platform.
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numerical investigation on the effects of fabrication conditions on fiber Bragg grating spectra using the phase mask technique
Applied Optics, 2013Co-Authors: Betty Kouskousis, Stephen F Collins, Daniel J Kitcher, Gregory W BaxterAbstract:A numerical investigation on how fiber Bragg grating fabrication conditions using the phase mask technique affect the harmonic components of the Bragg wavelength is presented. Both the properties of the phase mask and saturation effects are investigated to determine the underlying cause of the rise of various harmonic reflections other than the Bragg wavelength. Results are compared with published data by various authors.
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Fabrication of a π-phase-shifted fiber Bragg grating at twice the Bragg wavelength with the standard phase mask technique
Optics Letters, 2009Co-Authors: Zourab Brodzeli, Betty Kouskousis, Scott A. Wade, Gregory W Baxter, Claire Rollinson, Stephen F CollinsAbstract:A pair of reflection peaks/transmission dips, at twice the Bragg wavelength, were observed in spectra of a Type I fiber Bragg grating written with the standard phase mask technique. The occurrence of two peaks/dips, rather than one, is attributed to the interleaved refractive index modulations along the fiber core, with the periodicity of the phase mask that has been observed previously in images of gratings that cause destructive interference in a reflected wave at the Bragg condition owing to the π phase difference between the grating phases. Thus the standard phase mask technique produced an alternative type of π-phase-shifted grating at twice the design Bragg wavelength.
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Occurrence of features of fiber Bragg grating spectra having a wavelength corresponding to the phase mask periodicity
2008 1st Asia-Pacific Optical Fiber Sensors Conference, 2008Co-Authors: Sui P. Yam, Zourab Brodzeli, Scott A. Wade, Gregory W Baxter, Stephen F CollinsAbstract:Use of a phase mask with 536 nm uniform pitch allowed the fabrication of a fiber Bragg grating for use at a Bragg wavelength of 785 nm. Reflection and transmission features at 1552 nm, i.e. twice the Bragg wavelength, associated with the phase mask periodicity were observed. However, when phase mask orders other than plusmn1 were absent during fabrication the features at 1552 nm were not evident.
